A man suffered life-threatening injuries when someone struck him in the head with a handlebar in downtown San Francisco on Monday afternoon, police said.
The incident occurred at Hallidie Plaza, near the Powell Street BART station entrance, just before 3 p.m., according to police.
The victim, a 57-year-old man, was allegedly trying to break up a fight when the suspect, a 22-year-old man, attacked him.
Officers responded to the scene and medical crews transported the victim to a hospital.
Officers arrested the suspect as well as a 21-year-old man in connection with the assault. Their identities were not released.